Hohennagold Castle is a ruined castle situated on a hill, the so-called Schlossberg , overlooking the Black Forest town of Nagold. The hill consists predominantly of porphyritic rock. The ruins represent a relatively well-preserved 12th-century castle. The keep behind the curtain walls, a tower in the north-western corner of the complex as well as the outer ward with half-round and angular towers, are still visible. Around the castle there appears to have been a moat.An early medieval fortification was possibly erected at the location of the future castle around 750 by Count Ruodbrecht, one of Charlemagne’s uncles.